Kitt Peak Nightly Observing Program
Splendors of the Universe on YOUR Night!
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Aristarchus and Herodotus
Aristarchus is not a particularly large crater, but it manages to stand out as an extremely bright crater. Near the northwestern limb of the Moon, Aristarchus is more reflective than the darker Oceanus Procellarum surrounding it. Nearby crater Herodotus is similar in size, but different in appearance. Herodotus is shallower and darker.
Pythagoras is a large crater located nearly all the way to the western limb of the near side of the Moon. Because of our oblique viewing angle from Earth, it appears as a very elongated elliptical crater, but is infact circular. Its terraced walls and central peak are best viewed when near the terminator.
Schickard is one of the largest craters on the near side of the Moon. Near the southwestern limb of the Moon, it appears elongated due to foreshortening. The floor of Schickard varies in brightness, with a large bright patch in the center of the crater. It is thought that Schickard was first flooded with mare lavas, which look dark, and then the Orientale Basin impact event showered bright Highlands material onto parts of its floor, along with many small secondary craters.
Some craters on the Moon look elongated, because they are foreshortened, meaning we are seeing them at an angle. The closer the crater is to the limb of the Moon, the more foreshortened it is. Schiller, however, is actually an elliptical crater—very unusual. It’s hard to be sure how Schiller formed. Notice the linear ridges on one end of the elongated crater, dividing the floor in half, and the small crater on the opposite end, connected to schiller by a valley.
Mons Gruithuisen Gamma (left) and Delta (right) are two of many very interesting features found in or near the Mare Imbrium. Southwest of Sinus Iridum, they are more conspicuous than most lunar domes.
Rümker is actually a unique complex of a dozen or so overlapping lunar domes. Together, they make one big, bumpy dome, 73 km across. Like the typical, smaller dome, it is challenging or impossible to see unless the Sun is very low in the sky over it.
Mare Crisium is distinctly seperated from all of the other maria on the near side of the Moon, making it easy to distinguish. This round feature on the Moon is nearing the eastern limb, and so, is severly foreshortened—meaning, we are not looking at it straigh on, but at an angle.
Mare Humorum is one of the smaller mare on the near side of the Moon. It is situated on the western hemisphere, south of Oceanus Procellarum. It is estimated to be about 3.9 billion years old, and is the site of one fo the Moon’s mascons. Mascons, short for mass concentrations) have slightly higher gravity than the are around them. Mare Humorum has some striking ridges and rilles. A prominant crater, Gassendi interupts the northern “coast” of Mare Humorum—its floor cracked with many rilles. Yet another, smaller crater interupts Gassendi’s northern rim—creating a memorable figure of a ring with gemstone.
The Mare Imbrium Impact Basin formed when a large object crashed into the Moon 3.9 billion years ago. subsurface lava rose to flood the giant crater, eventually solidifying into a younger, smoother terrain. Prominent features of Mare Imbrium include the crater Plato to the north, with a dark crater floor; Sinus Iridum (meaning Bay of Rainbows) to the northwest, with the Montes Jura mountain range forming a distinct C-shaped knob on the edge of the mare; and the 3 mountain ranges—Montes Alpes, Caucasus, and Apenninus—that mark the eastern edge of the mare.
Also known as a twilight zone, a terminator is where the shadow of night and the light of day come to meet on a planetary body. At the edge of where the Sun’s light reaches, the terminator is constantly moving as the Moon rotates. When observing the Moon, many features are best observed when they are near the terminator, where shadows are long and plentiful. The shadows provide higher contrast between surface features.
This is the largest sinuous rille on the Moon. It is about 3 km wide at its western end, and widens up to 6 km toward the eastern end, where you will find the Cobra Head. The Cobra Head is a steep volcanic depression near the top of a mountaid at the end of the snake-like sinuous rille. Shcröter’s Valley may have been a major source of the lava that formed the Oceanus Procellarum.Schröter’s Valley is part of the Aristarchus Plateau, and is foundto the immediate northwest of the small, but very bright crater Aristarchus.
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Nightly Observing Program. Most of the above images were taken as
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